Hutchinson ? A 15-year-old Hutchinson High School student has been arrested in an explosion of a homemade device at the home of a Nickerson school teacher, authorities said.

The arrest Monday of the Hutchinson boy on one count of arson was the second in the investigation of a string of homemade explosives. A 17-year-old Nickerson High School student was arrested Friday.

The latest arrest was tied to an explosion Jan. 28, said Reno County Sheriff Randy Henderson.

“The boy knew some of the kids involved, even though he went to school in Hutchinson,” Henderson said.

While some targets of the devices, which destroyed mailboxes and shattered a car windshield, were Nickerson school employees, the other detonations appear to be random acts, said Reno County Dist. Atty. Keith Schroeder.

“If you are looking for a clear-cut motive for all these events, I don’t think it exists,” Schroeder said.

The first reported explosion occurred Jan. 16 in Hutchinson, and subsequent explosions were reported in Nickerson, Sterling and rural Reno County. Three of the 10 devices did not go off.